The Sudoku Watch, a concept from Tokyoflash Design Studio, is not – as you might assume – a watch on which you can also play Sudoku.

Oh no.

You have to complete the Sudoku puzzle to read the time, which means that time will inevitably have moved on since you started and you’ll have to complete another Sudoku puzzle to read the time, which will have moved on by the time you’re done, at which point…